The Fratellis break out of jail and for revenge, kidnap all of the Goonies but Mikey, then tell him he has to come to their hideout if he wants to save them. They've also kidnapped Annie the Mermaid. I am not making this up.

So you play Mikey, and you have to travel through the Fratellis' labyrinthine hideout (a map is required, because you will get lost if you don't have one), which apparently contains portals to other universes. You encounter such characters en route such as Old Man ("Welcome here! This is a warp zone!"), Old Woman, Fish Man and Konami Man (Konami's mascot who appeared in numerous games, usually as a cameo). Mama, Jake and Francis are joined by their cousin Pip-Squeak Fratelli. Sloth is completely absent from the game. Once you've tracked down and rescued all of the Goonies, you have to find Annie and free her. HURRAY FOR KONAMI AND THE GOONIES!

Despite having a ridiculous plot involving mermaid kidnapping, it's a hell of fun game. It's got a very Metroid feel to it. I recommend it if you're a Goonies fan in the slightest, and are into NES games.